Dynatrace Load - Dynatrace Load lets you test the performance of web and mobile applications with the realism of load generation from the cloud.
StresStimulus - Load testing tool for websites and mobile that works with hard-to-test applications.
Apache JMeter - Apache JMeter™.
OctoPerf - OctoPerf is a SaaS load testing solution, based on JMeter.
Sitespeed - Sitespeed.io is an open source tool that helps to analyze and optimize website speed and performance.
SmartMeter.io - Performance Testing with Enterprise-Level Features with a familiar jMeter interface